how to include cabal macros

[joeyh]

I'm having problems like this:

hothasktags: Cannot expand #if directive in file Annex.hs at line 83 col 1: MIN_VERSION_exceptions(a,b,c) is not a defined macro

(Oddly, earlier versions of hothasktags seemed to work.)

While I can work around with with -D 'MIN_VERSION_exceptions(1,1,1)', new version macros are added from time to time..

Seems that the solution could be to -c --include=dist/build/autogen/cabal_macros.h to get all the macros. But that fails:

Parse error: SrcLoc {srcFilename = "./dist/build/autogen/cabal_macros.h", srcLine = 1, srcColumn = 1}: Parse error: /*

The problem is the /* */ comments in the file.

I have worked around that by preprocessing the .h file before calling hothasktags, to remove the comments.

[luqui]

Hmm... I don't really have the context for this, but it sounds like haskell-src-exts is not understanding /* ... */ comments correctly. Do you think patching haskell-src-exts would be the best overall solution here?

[joeyh]

/* .. */ is not a valid haskell comment, so it does not seem right for haskell-src-exts to support it.

At least with my version of ghc (7.6.3), when cabal runs ghc with the parameters "-optP-include","-optPdist/build/autogen/cabal_macros.h", ghc in turns runs cpp (not cpphs), and in this case, cpp strips out the C-style comments while preprocessing. This is why ghc does not have trouble with those comments.

Ah, cpphs has a way to do this comment stripping too: --cpp -traditional.

So, this works: hothasktags -c --cpp -c -traditional -c --include=dist/build/autogen/cabal_macros.h

But is quite a mouthful, and not easy to work out. Perhaps hothasktags could have an option to make it use the cabal macros and enable those options?

[joeyh]

With cabal's new v2 commands, an easier way to run hothasktags is:

cabal exec hothasktags -- --cpp

That makes it find the cabal_macros.h and generally use the same stuff cabal used to build the package. It seems the --cpp is still necessary, as is enabling with -X any extensions that the cabal file has in Default-Extensions.

[luqui]

Thanks for this information